INTEGRATED OPTICAL RING-RESONATOR WITH MICROMECHANICAL DIAPHRAGM FOR PRESSURE SENSING

An optical pressure sensor has been fabricated which uses an integrate d-optical ring resonator to measure the strain induced in a micromachi ned silicon diaphragm. A silicon substrate is etched from the side opp osite the silicon oxynitride optical waveguides to produce a rectangul ar diaphragm whose long edge lies underneath a straight section in the ring. Pressure-induced changes in the resonant frequency of the ring are measured using a frequency swept laser diode. A linear response to pressure is observed for the TM mode with a sensitivity of 0.0094 rad /kPa. This pressure sensor is rugged, is amenable to batch fabrication , and it provides a link-insensitive readout.